The use of ferrite material, such as, yttrium-iron-garnet, to provide frequency selective limiting is well known. The advantages of subsidiary resonance limiting is also recognized in the prior art.
The closest, best known prior art is believed to be found in the following references: U.S. Pat. No. 3,906,404 to patentee Dixon, Jr.; U.S. Pat. No. 4,027,256 to patentee Dixon; publication "Interaction of Signals in Ferromagnetic Microwave Limiters" by P. R. Emtage and S. N Stitzer in IEEE Transactions on Microwave Theory and Techniques, Vol. MTT-25, No. 3, March 1977, pp. 210-213; and publication "YIG Rod Ferrite Limiter with Extended Dynamic Range" by Samuel Dixon, Jr., in IEEE Transactions on Magnetics, Vol. MAG-14, No. 1, January 1978, pp. 28-30.